`Chain of Command' is an intimate portrait of what has been dubbed "the war of this generation" - the US military's mission to combat violent extremism around the world - and the men and women devoting their lives to it. Filmed over 18 months, the eight-part documentary allows viewers unprecedented access inside the Pentagon to see how decisions made there have a direct impact on service members fighting on the front lines to protect Americans and US allies from radicalised extremists. The series also includes a rare on-camera sit-down with Gen Joseph Dunford Jr, the chairman of the Joint Chiefs of Staff.